Some readers may recall the story of Joseph Casias, the model employee who was fired from his job at Wal-Mart for using medical marijuana in accordance with state law. The ACLU was in court today to argue that an appeals court should reinstate a lawsuit we filed on Casias' behalf, charging Wal-Mart and the manager of its Battle Creek, Mich., store with wrongfully firing him.

Casias has suffered for more than a decade from sinus cancer and a softball-sized brain tumor in his head and neck that makes it difficult to speak and causes severe and constant pain. Like many medical marijuana patients, he found only minimal relief from most pain medications, which as a side effect caused him to suffer from severe nausea.

That's why, after Michigan voters passed the Michigan Medical Marihuana Act in 2008, Casias' oncologist recommended that he try marijuana, and so he obtained the appropriate registry card from the Michigan Department of Community Health. The results were immediate and profound: his pain decreased dramatically, the new medicine did not induce nausea and he was able to gain back some of the weight he had lost during treatment.

In accordance with the law, Casias — the 2008 Associate of the Year at Wal-Mart's Battle Creek location — never ingested marijuana while at work and never worked while under the influence of marijuana. Wal-Mart fired him for testing positive for marijuana anyway.

The Michigan law protects medical marijuana patients from "disciplinary action by a business," but a district court judge nevertheless dismissed our lawsuit on behalf of Casias in February 2011. During oral arguments today, the ACLU asserted its case should be reinstated because the lower court ignored the text of the state's medical marijuana law prohibiting companies like Wal-Mart from firing patients like Casias.